1. Field of the Invention
This invention relates to a process and apparatus for manufacturing individual items such-as pieces of jewelry having a personalized message, or design, as part of the jewelry in either prominently embossed or in sharply sunken features. More particularly, this invention relates to a jewelry manufacturing process and apparatus utilizing photopolymerizable resin backed by a rigid substrate for creating a plug comprising a multi-level partial mold, for use in combination with other molds, in a "lost wax" type casting process.
2. Description of the Prior Art
Personalized jewelry bearing the wearer's name or other message are popular products. An example of such a jewelry item may be a high school class ring identifying a social affiliation, date of graduation, and the name of the high school mascot. Other such jewelry items could include pendants, charms, name tag bracelets and the like. Although such jewelry items have been available in the past, they have been available with only a limited selection in the style, or letter font, and in many cases long names or unusual names were not possible in an attractive form. These limitations on the availability of personalized jewelry are mainly due to the lack of a convenient and inexpensive method of manufacturing such jewelry. The methods of manufacturing personalized jewelry which are presently available have limited flexibility, are labor intensive, and produce results with limited eye appeal.
These prior methods include hand and machine engraving. Hand engraving, of course, required a skilled artisan and the results were limited by his or her ability. Although machines are commonly available to engrave letters, these machines frequently included a pantograph arrangement that operated off preformed letters on a die. Only the simplest letter styles were possible, and the selection of letter designs was extremely limited. The letters frequently had to be spaced and arranged individually by hand on the jewelry item. In addition, in both hand and machine engraved jewelry, only a very shallow message is possible without great expense and the shallow message is not as appealing to the eye or as durable as the personalized jewelry which can be manufactured using the method of my invention.
Die striking is another method of providing personalized messages on jewelry. In this method, the letters are impressed into the jewelry item by striking the jewelry with a hardened steel die to form the letters. This method either requires a specific die to be made for each name or requires the message to be reproduced letter by letter. Because of the expense of making special dies for specific names, this method is reasonably applicable with only common first names. In addition, with this method, only a limited selection of letter styles is available. As with the engraving method only a shallow recessed message is available and the method does not provide the deeply sunken and attractive name or message available with my invention.
Another method used currently is the injection molding of individual letters in plastic which are placed individually by hand in a specific slot in the wax pattern that is used to make the mold for casting the jewelry item by the lost wax process. This method requires the message to be assembled by hand on each individual wax pattern from the letters available and does not permit a collection of patterns for common names to be reused a multiplicity of times, which would reduce the cost of manufacture of subsequent jewelry items. Furthermore, this method requires molds which are costly for use in injection molding machines to form the individual letters.
Canadian Patent No. 1,102,092 introduces into the investment casting or lost wax process of manufacturing jewelry the manufacture of inserts for a master die or wax pattern with multi-level alphabet messages using the output of a conventional typewriter to photo-etch names, messages and designs.
The Canadian patent discloses preparing a plurality of personal messages to be included on individual pieces of jewelry, photographing the plurality of personal messages and making a photographic negative with an image of the messages, using the photographic negative and a source of radiation to polymerize a photopolymerizable resin carried on a rigid substrate and removing the unpolymerized photopolymerizable resin from the substrate to form the plurality of personalized messages, placing a plurality of insert forming rings about each personalized message, filling the rings with a fluid casting material, curing the fluid casting material within the rings to form a plurality of solid inserts, placing each insert in a master die and injecting the master die with wax to make a wax likeness of the jewelry bearing the personalized message, and using the wax likeness to form the cavity of a mold in which the personalized jewelry is to be cast by the lost wax process. The Canadian patent does not contemplate removing the unpolymerized photopolymerizable resin from the substrate in stages using a blocking agent and resulting in multi-level personalized messages.
U.S. Pat. No. 4,444,607 issued to Lash et al., discloses a process for molding a three dimensional decorative article which includes electronically generating a line drawing of an article and electronically displaying the drawing, photographing the drawing thereby creating a transparency, positioning the transparency over a layer of liquid photopolymer, exposing the photopolymer through the transparency to a burst of radiation to set the photopolymer, and removing the remaining liquid to form a three dimensional article. Using a liquid photopolymer in jewelry manufacturing, however, is not practical due to the unique machinery and manufacturing methods employed in this highly specialized industry.
U.S. Pat. No. 4,889,666, issued to Kawasaki, discloses a METHOD FOR PRODUCING CONCRETE PRODUCTS PROVIDED WITH INLAID PATTERNS whereby a reusable mold with recessed patterns is produced by emitting ultraviolet rays on opposing surfaces of an ultraviolet setting masked resin, and using the resulting three-dimensional form in a "lost-wax" type casting operation. However, this disclosure requires extra steps of irradiating the photopolymer from both sides to produce a reusable mold, and creating a "waste" mold from the reusable mold.
U.S. Pat. No. 3,659,327, issued to Beverick et al., teaches the manufacture of jewelry depicting various scenes or figures by creating a negative of an image, placing the negative on a zinc plate by photoengraving, creating an impression in a conventional rubber-based impression material thereby producing a reverse or negative impression of the image, filling the impression with wax to form a likeness of the finished casting, investing the wax likeness into a casting ring filled with high heat plaster, and heating the plaster whereby the wax is burned off leaving a plaster mold into which a gold article may be cast. Beverick, however, requires the additional step of manufacturing a wax mold in lieu of using the initial photoengraved material to create a final mold.
Thus there exists a need for a jewelry manufacturing process whereby a photographic negative is produced from a computer-generated image, the negative is used to mask "hard" photopolymerizable resin, backed by a rigid substrate, which is exposed to ultraviolet radiation thereby producing a multi-level positive three-dimensional likeness of the object to be cast, creating a negative mold of the image for use as an insert plug in combination with other molds having apertures formed therein for receiving said plugs thereby creating a complete mold of a finished jewelry item.